A study has found that Abbott Lab's ID Now COVID-19 test missed as many as half of the cases found to be positive by another test.
The study, which has not been peer-reviewed, was published on Tuesday in Bioxriv. In it, researchers from New York University assessed 101 dry nasal swabs and 101 nasopharyngeal swabs from the same patients to compare the ability of Abbott and Cepheid's Xpert Xpress SARS-CoV-2 tests to detect SARS-CoV-2 viral nucleic acids.
They found that while initially the ID Now COVID-19 assay performed well, as the viral load decreased, the Abbott test produced more false negatives. According to the authors, Abbott's test missed one-third of the samples detected positive by Cepheid's test when using nasopharyngeal swabs, and 48% of the samples detected positive when using dry nasal swabs. Samples were provided by NYU's Langone Tisch Hospital, the paper said.
While the researchers said that they use the Cepheid Xpert Xpress SARS-CoV-2 test and Roche's Cobas assay in their labs, they wanted to explore a test with a shorter turnaround time. The ID Now COVID-19 assay, they said, provides results in as little as five minutes, compared to 45 minutes for the Cepheid test running on the company's GeneXpert Dx instrument, and 3.5 hours for the Roche assay.
The Abbott point-of-care test has one of the fastest time-to-results of any COVID-19 test on the market, and when it was issued emergency use authorization from the Food and Drug Administration, some saw it as an urgently needed tool for rapidly diagnosing COVID-19. President Trump called it "a whole new ballgame" and the test is now used by the White House to test officials and screen visitors.
But based on their results, the NYU researchers said that if the ID Now COVID-19 test were to be used for first-step screening, "confirmation of over 80% of the tested samples would be required to be confident that the negative results are truly negative." However, the authors said the high specificity and positive predictive value mean "a positive result can be interpreted as a true positive."
An Abbott spokesperson said in an email that the results of the NYU study weren't consistent with other studies of the ID Now test. "Abbott has distributed more than 1.8 million ID Now tests and the reported rate of false negatives to Abbott is at .02%, which we've previously shared with the FDA," the spokesperson added.
"It's unclear if the samples were tested correctly in this study," she said. "In communications with other users of the test, it is performing as expected."
On its first quarter financial earnings call, CEO Robert Ford said Abbott had the capacity to produce 50,000 ID Now tests in April, increasing to 2 million tests per month by June.
Robert Boorstein, medical director for oncology and esoteric testing at Brooklyn-based Lenco Diagnostic Laboratories, noted he doesn't have direct experience with either Abbott or Cepheid's tests, but said in an email that he thinks the paper is a good one. He noted that the problem may not be isolated with Abbott and asked whether the FDA was in too much of a rush to get SARS-CoV-2 tests onto the market.
"Has the FDA relaxed rules for bringing tests to market to such an extent that tests are being offered that do not meet the claims made for them?" he asked.
Further, he questioned whether labs are under so much pressure to do these tests that they're either not verifying the tests or are "ignoring verification results that show the tests don't work properly?"
The NYU study is not the first to question the accuracy of Abbott's test. The Cleveland Clinic conducted a separate study and found that ID Now COVID-19 had a false negative rate of 14.8%, the NYU researchers said. They noted that samples in that study were stored in viral transport media, instead of being inserted directly into the ID Now platform, which may have compromised the test's accuracy.
Following the Cleveland Clinic research, Abbott recommended the use of dry swabs for best results, but the NYU team said that "Contrary to manufacturer expectations, our parallel study showed that the sensitivity of Abbott ID NOW using dry swabs (51.6%), was actually lower than when using viral transport media (66.7%) as seen from our earlier study of [emergency department] samples."
"Our study revealed low sensitivity with high false negative results by Abbott ID Now platform irrespective of use of viral transport media, which raises concern regarding the performance of the assay and its suitability as a diagnostic tool for symptomatic patients," the NYU researchers wrote.
Boorstein added another question to consider in light of the NYU study. "Are companies ignoring reports of problems with tests, and are labs pressured to use tests which perform poorly under threat of being denied allocations of scarce equipment or reagents?" he asked.
This story first appeared in our sister publication, Genomeweb.
